Table 3.

Population results for systematic and random errors in tumor, left lung, right lung, and spinal cord position relative to the first ABC helical CT scan (n = 9, except for right lung where one patient was excluded due to pleural effusion). All data reported in mm.

	GTV			Left Lung			Right Lung			Spinal Cord
	L-R	A-P	S-I	L-R	A-P	S-I	L-R	A-P	S-I	L-R	A-P	S-I
Systematic Error (Σ)	3.6	3.9	6.7	1.4	1.3	3.4	1.0	0.7	3.3	0.8	0.7	2.0
Random Error (σ)	3.1	3.1	3.9	1.5	1.7	2.6	1.5	1.2	2.6	0.8	0.5	1.6

Abbreviations: L-R, A-P, and S-I represent left to right, anterior to posterior, and superior to inferior, respectively.